Commonly, video cameras are marketed that are provided with a monitor screen section in the form of a housing separate from a video camera main body (which is hereinafter referred to as a VTR section). In such a video camera, a structure is formed in which the VTR section and the monitor screen section are connected by a two-shaft hinge device. Firstly, the monitor screen section is turned horizontally relative to the VTR section, about a first rotation shaft of the two-shaft hinge device, and opened out to a position orthogonal to the VTR section. Then, in this opened state, the monitor screen section is turnable about a second rotation shaft of the two-shaft hinge device.
In a video camera provided with this kind of two-shaft hinge device, if the two rotation shafts of the two-shaft hinge device are rotated simultaneously, corner portions of the housing of the VTR section and the housing of the monitor screen section collide, and there is a possibility that either of the housings will be damaged.
Accordingly, in this kind of video camera, the VTR section and the monitor screen section are constituted with a two-shaft hinge device with a rotation-limiting function. Thus, turning of the monitor screen section is enabled when the monitor screen section has first been opened to be orthogonal to the VTR section, and it is possible to prevent the VTR section and the monitor screen section from colliding and causing damage.
Thus, the following structure has been proposed as a structure of a conventional two-shaft hinge device with a rotation-limiting function.
A recess section at which a portion of a shaft section is cut away is formed at each of a first rotation shaft and a second rotation shaft. The first rotation shaft and the second rotation shaft are made perpendicular at the positions of the recess sections, and the perpendicular portion is rotatably supported by a retention member. Here, a distance at the perpendicular position between an axis of the first rotation shaft and an axis of the second rotation shaft is set to a distance such that; in a position at which the recess section of the first rotation shaft is opposed with the second rotation shaft, the second rotation shaft is rotatable, but when the recess section of the second rotation shaft opposes, at the position opposing the first rotation shaft, a portion other than the recess section of the first rotation shaft, an end portion of the recess section of the second rotation shaft touches against the first rotation shaft and is non-rotatable.
Furthermore, the distance is set such that, in a position at which the recess section of the second rotation shaft is opposed with the first rotation shaft, the first rotation shaft is rotatable, but when the recess section of the first rotation shaft opposes, at the position opposing the second rotation shaft, a portion other than the recess section of the second rotation shaft, an end portion of the recess section of the first rotation shaft touches against the second rotation shaft and is non-rotatable.
Thus, it is not possible to simultaneously rotate both the first rotation shaft and the second rotation shaft (see, for example, Patent Reference 1).
As described above, in a two-shaft hinge device with a rotation-limiting function that is employed in a conventional video camera, it is necessary to cut away and form recess sections in each of a shaft radial portion at the middle of the first rotation shaft and a shaft radial portion at the middle of the second rotation shaft. Therefore, it is difficult to reduce the length in the shaft direction of either of the first rotation shaft and the second rotation shaft. Moreover, to increase a distance between the first rotation shaft and the second rotation shaft, it is necessary to increase either of the shaft diameter of the first rotation shaft and the shaft diameter of the second rotation shaft.
Given this, it is difficult to reduce the size of the conventional two-shaft hinge device with the rotation-limiting function.
Meanwhile, in a portable telephone device of a type that folds in two, push buttons are disposed at a first housing and a liquid crystal monitor that displays images is incorporated at a second housing, and a reduction in size of a two-shaft hinge device with a rotation-limiting function that connects the first housing with the second housing is desired.
Furthermore, for recent double-folding type portable telephone devices, it is desired that it should be possible, with a single hinge device, to open out the first housing at which push buttons are disposed and the second housing in which a liquid crystal monitor that displays images is incorporated in two directions; for example, an opening direction in which the second housing is turned about a first rotation shaft and arranged in a longitudinal direction of the first housing, and an opening direction in which the second housing is turned about a second rotation shaft and arranged in a lateral direction of the first housing.
However, if the two-shaft hinge device with a rotation-limiting function that is employed in conventional video cameras is employed as is, from a state in which the monitor screen section is closed, opening in the longitudinal direction that is turned about the first rotation shaft is possible but turning about the second rotation shaft to open in the lateral direction is not possible.
Patent Reference 1: Japanese Patent No. 3,496,445